Building material for building elements, and a method and a system for manufacturing said elements

ABSTRACT

A method and apparatus or system for the continuous manufacture of building element consisting of a self-supporting framework of tightly compressed solid particles and a foaming material in the shape of a foamed plastic material, includes the use of a filling station where mold bottoms are placed in series on a roller conveyor, assembled with sidewalls and passed along a guide section, wherein particle-shaped filler is supplied from a silo while premixed foam material is injected into the material through nozzle tubes and the components are mixed before being injected into the mold and compressed. After placing of a top wall on each of the molds, these are passed under a roller conveyor, and while the molds are moved ahead between the roller conveyors and possibly roller conveyors outside the sidewalls, the foam material binds the particles together to form a monolithic unit which will set before the molds leave the roller conveyors. After demolding of the formed flow of the material, it is cut by a cutting mechanism into the required lengths and the molds are carried back to the filling station. The product is a building element of firmly compressed hard expanded burnt clay particles forming a coherent supporting skeleton of abutting particles bound together by a cured polyurethane foam in only an amount sufficient to fill the cavities between the compressed particles.

The present invention relates to a building material for a buildingelement in the shape of a plate, block, beam or column and consisting ofa compressed, hard, particle-shaped filler, the particles of which areheld together by a foam plastic material.

Lightweight building elements of foam plastic, containing as admixtureand economizing means a filler in the shape of hard particles, aregenerally known. In manufacturing these known building materials it isattempted to achieve a distribution of the particles of maximumuniformity, and a complete embedment of each particle in a surroundingmass of foam plastic. A prior art building element of this kind may beproduced, e.g. as described in the German Published Patent SpecificationNo. 2056063, where a mixture of particles and perlite and polyurethanefoam is compressed in a mould by the upper portion of the mould beingpressed down into the lower portion thereof at the same time while thefoaming is taking place. The compression, however, is not stronger thanthat the frothing agent is deposited between the particles in a waydescribed as "a kind of mesh formation of the frothing agent in thePerlit-filling".

While the prior art building elements of the kind in question aredeveloped with a special view to producing heat and sound insulatinglightweight building elements, it is the object of the present inventionto provide a cheap building material which in addition to its goodinsulating and fire-restraining qualities comprises such a strength aswell that it can be used as a supporting element in buildingconstructions, e.g. in such a manner that they can replace usualreinforced concrete building elements which regarding weight as well asinsulating qualities are inferior to the building elements according tothe invention. Furthermore, it is the object of the invention to providea method and a system for manufacturing building elements.

The building material according to the invention is characteristic inthat the particles of the filler are so firmly compressed that they forma coherent supporting skeleton or framework, and that the foam plasticmaterial, preferably a polyurethan foam, is occurring only in aprecisely sufficient amount for filling the existing natural cavitiesbetween the firmly compressed particles for cementing the particlestogether.

The filler is compressed so firmly in the mould that after the foamingthe grains will still touch each other. This is the condition ofobtaining high compression strengths.

Such a building material comprises a great number of favourablequalities, which it has not been possible to combine in any hithertoknown homogenous building material. The self-supporting framework andthe limitation of the foam material to the natural cavities thereincause the building material to combine a high strength and stabilityagainst contraction and shrinkage with excellent fire-restrainingqualities and highly satisfactory surface qualities. In case of fire,the material is in fact self-extinguishing, and the relatively greatamount of particles (e.g. 85-90% leca) and the corresponding smallamount of foam plastic (e.g. 10-15% polyurethane) moreover have theeffect that the problems generally occurring in connection with castingof thick elements of foam material owing to developed heat destroyingthe foam, are eliminated in consequence of the reduced generation ofheat from the foam and the absorption by the particles of the surplusheat. The tensile strength of the material is furthermore easilyimproved by embedding fibres or inserting reinforcement, e.g. ofaluminium. In addition to improving the tensile strength, inorganicfibres will in case of fire have a stabilizing effect, as when meltingthey cooperate to cement the inorganic filler together so that this willnot disintegrate when the foam plastic material carbonizes. This resultsin a sintering of the material which acts as a heat shield preventing afurther intrusion of fire. The material is easily workable, it will holdnails and can be glued. The surface which, besides, is walkproof can begiven a smooth surface which is well suited to be painted. Theproduction rate for this material, which is a few minutes, makes itparticularly suited for a continuous manufacture of elements.

The building material is easily produced by a method in which foamingagents in a liquid state are amalgamated with the filler before saidfiller is introduced into a mould, the material thereafter beingcompressed in said mould, and this method is characteristic in that allcomponents are injected into the mould through a common mixing nozzle inwhich loose particles of the filler and possible fibres or the like areinjected with compressed air and mixed with premixed injected foamplastic material.

From the German Published Patent Specification No. 2017548 it is knownto supply particles of a filler moving downwards under the influence ofthe force of gravity, with a foaming material by means of an annularnozzle surrounding the supply tube for the particles, but noparticularly intimate mixing is obtained thereby, especially not when itis a question of such relatively small quantities of foaming material asthose used for cementing the particles of the building element accordingto the invention together. By the injection of the particles of thesuspension in an air stream and the simultaneous inflow of the premixedfoaming components, however, it is possible to obtain an effectiveenveloping in the mixing nozzle of all particles with foam plastic, andby injecting the material into the mould under pressure, it iscompressed. The method of injection with compressed air involves theadvantage that the ventilation of the mould necessary for removing thepressure above the atmosphere, will remove deleterious gasses withoutany further exsuction being required.

Contrary to the known mixing nozzle, the nozzle according the inventionowing to the stream of particles and the compressed air will beself-cleaning so that it can be started and switched off without beingcleaned.

The casting of building elements may be performed in a manner known perse in common closed moulds and, further, in moulds which are open atboth ends, as according to the invention the mixture of filler andpremixed foam plastic material is injected from the mixing nozzlethrough one or more nozzle tubes placed in the direction of movement ofthe moulds and ending at a place in the mould, where the compression ofthe filler is initiated. This permits an even distribution of thematerial in the mould during continuous casting, whether the mould isstationary and the casting machine is moving along said mould, or viceversa the mould is moving in the longitudinal direction, e.g. on aconveyor belt or a roller conveyor. If desired, additional chemicals oradmixtures, e.g. fibres of glass or polypropylene may easily be added bybeing injected into the mixture, thereby achieving an even addition ofthe fibres which are distributed homogenously in the product withoutflocculation.

In addition to the compression obtained by foaming of a two-componentmaterial, such as polyurethan, it is possible to provide a furthersecurity that the solid particles will form a firm coherent framework byaccording to the invention moving the opposed sides and/or the top andbottom plates of the mould towards each other in a manner known per se.A corresponding method is known from the U.S. Pat. No. 3,560,599, wherethe object, however, is not the obtaining of a further compression ofthe cast material, but is the obtaining of a regular convex top sidethereof. The compression may also be performed by means of one or morepistons or by vibrating elements.

The building element according to the invention or possibly severalsuccessive building elements according to the invention may be producedin a system of the kind referred to hereinafter. The injection of themixture of particles and foaming components from the common mixingnozzle through the nozzle injection tubes extending in the longitudinaldirection of the mould, ensures an even distribution of a homogeneous,continuously manufactured material which is thereafter compressed.

In the building element, reinforcement bars, tubes or corresponding barsand tubes are easily incorporated during production.

In the following the invention is explained in details in connectionwith an embodiment of the system according to the invention formanufacturing building elements of a compressed, self-supportingframework of filler, the cavities of which are filled with a foamedplastic material.

In the drawing

FIG. 1 is a schematic side view of the system,

FIG. 2 is a schematic cross-section through an embodiment of a mould tobe used in the system,

FIGS. 3 and 4 are cross-sections through two different moulds to be usedin a system of the kind shown in FIG. 1, and

FIG. 5 shows an injection device comprising a mixing nozzle for mixingand injecting filler particles and premixed foaming material.

The system comprises a roller conveyor 1 supporting mould bottoms 2which are carried through the system in continuation of each other.Also, the system comprises a roller conveyor 3 having rollers pressingagainst the top side of the top wall 4 of the moulds, and rollerconveyors 5 having rollers pressing against the opposed side walls 6, 7of the moulds.

The mould bottoms 2 are introduced into the system at A to the left inFIG. 1 where, if desired, they can be provided with a reinforcement or acoating forming the outer side of the finished building element. At Bthe mould bottom passes into a firm guide section 8 which is suppliedwith particle-shaped filler from a silo 9 after the mould bottom 2having been assembled with the side walls 6, 7. A foam plastic,preferably polyurethan with added foaming means, is injected through oneor more nozzle tubes 12. In the guide section 8 the material iscompressed by means of a piston mechanism 10 or screw conveyor--possiblyduring simultaneous vibration--and the top walls 4 of the moulds areplaced thereon before the moulds pass under the roller conveyor 3 andbetween the roller conveyors 5. If desired, a sheet of film 11 may bedrawn along under the top wall 4 of the mould which is open at bothends, in order that the top wall will easily release the material duringthe demoulding and possibly in order to form a sealing in the mould.

As indicated in FIG. 2, the side walls 6 and 7 may be adjusted inlateral direction by side roller conveyors 5 for adjustment of the widthof the finished element. Moreover, the roller conveyors 5 may be soadapted that they press the side walls 6 and 7 inwards towards eachother immediately after the mould having passed the mouth of the guidesection 8. The foam plastic is injected into the mould under such apressure and in such an amount that it fills the cavities between theparticles and cements them together to a firm monolithic compound duringthe foaming and hardening of the foam plastic.

It will be understood that when producing lightweight elements it willbe possible to use a stationary guide section and a moulding andcalibration tube which is connected to the discharge end of said guidesection and through which the flow of material will pass and from whichit comes out in cured condition. In case of larger objects, such asbuilding elements, however it is necessary to use on the section E-F,the above mentioned roller conveyors or possibly endless bands carryingmould bottoms, top walls and side walls, respectively.

On the section F-G, the flow of material is demoulded, and at G it iscut in required lengths. As indicated by arrows the mould bottoms andwalls are carried back to the filling station, possibly after havingbeen cleaned. If desired, the mould bottoms, however, may be replaced bypre-fabricated plates, such as chip boards, plates of asbestos-cement,or other plates which remain on the manufactured objects, forming asurface coating. Bars of aluminium or steel for reinforcement ofsupporting structures may be inserted through the guide section 8through arbitrarily chosen holes. Electric tubes or tubes for otherpurposes may be inserted in the same way.

If the system is used for the manufacture of building elements having aconstant width, and in cases where it is not necessary to perform anadditional compression of the filler, the moulds may simply be formed asshown in cross-section in FIG. 3. FIG. 4 shows a cross-section through amould having an adjustable width. This mould is adapted for compressionof the material by pressing the side walls together under the influenceof outer roller conveyors.

FIG. 5 shows schematically an apparatus for mixing and injecting thematerial into the moulds. The apparatus comprises a silo 9 forparticle-shaped filler which is injected by means of a blower 18 into amixing nozzle 13 which is adapted to receive as well, premixed plasticfoam from a sprayer 15. From the nozzle 13 the ready mixture is injectedinto moulds as shown, or possibly in stationary moulds havingcompression devices which are known from the manufacture of concrete.

Blown-in fibres 17 or other admixtures may furthermore be supplied inthe mixing nozzle 13.

Compressed-air nozzles 16 increasing the turbulent flow and promotingthe mixing process may be inserted in the mixing nozzle 13. Thesenozzles may also be important to the cleaning of the mixing nozzle.

Dosing devices 18 of known adjustable types are situated at the placeswhere the material is supplied.

By the method and the system according to the invention it has becomepossible in one single process to produce continuously in accordancewith the assembly line method, monolithic reinforced building elementswhich are self-supporting, highly insulating and fire-restraining inconsequence of the heavy compression of the cemented solid particles andof the foaming material of the self-extinguishing type cementing theparticles together. Moreover, it has become possible to produce in asimple way such elements having any desired surface structure andcoating.

I claim:
 1. A building element comprising a body of firmly compressed hard expanded burnt clay particles forming a coherent supporting skeleton of abutting particles bound together by a cured polyurethane foam in only an amount sufficient to fill the cavities between the compressed particles.
 2. A building element according to claim 1, wherein said clay particles are present in an amount of from about 85 to 90 percent, and said polyurethane foam in an amount of from about 10 to 15 percent.
 3. A method of producing a building element, comprising premixing in a mixing nozzle hard expanded burnt clay particles and a foamable polyurethane binder under the influence of compressed air, discharging through a nozzle the mixture so produced while injecting the same under compressed air pressure into a mold, and compressing the mixutre sufficiently to cause said particles to contact each other during curing of said foamable polyurethane.
 4. A method according to claim 3, wherein said mold is caused to move in a linear direction and said mixture is injected through a nozze disposed in the direction of movement of said mold and at a position where compression of said mixture is initiated.
 5. A method according to claim 4, wherein at least two of the top, bottom and side portions of said mold are caused to move inwardly with respect to each other to compress said mixture.
 6. A method according to claim 3, wherein inorganic fire resistant fibers are added to said mixture during premixing thereof, said fibers being capable of melting when exposed to fire to cement said particles together.
 7. A method according to claim 3, wherein said premixing and injection of said mixture are conducted continuously and simultaneously, and said mold is moved continuously, said foamable polyurethane reacting sufficiently fast to cause curing thereof before the building element leaves the mold.
 8. A method acording to claim 3, wherein the bottom of said mold is a pre-fabricated plate which is caused to adhere to the cured polyurethane and form a surface of the building element so produced.
 9. A system for manufacturing a building element, comprising a mold having top, bottom and side walls adapted to compress a foamable mixture to be molded, a mixing nozzle for premixing and injecting a mixture of foaming components into said mold, means for introducing into said premixing nozzle compressed air and particulated filer material, spray means for spraying into said premixing nozzle a foamable plastic binder, and a nozzle injection tube connected to said mixing nozzle for injecting said premixed mixture into said mold.
 10. A system according to claim 9, which further comprises means for blowing fibrous filler material into said premixing nozzle.
 11. A system according to claim 9, wherein said nozzle injection tube is disposed at guide means for said molds, and means are provided for compressing said mixtures as it is discharged from said nozzle injection tube. 